Plasma enhanced atomic layer deposition (PEALD) equipment and method of forming a conducting thin film using the same thereof

ABSTRACT

A plasma enhanced atomic layer deposition (PEALD) apparatus and a method of forming a conductive thin film using the same are disclosed. According to the present invention of a PEALD apparatus and a method, a process gas inlet tube and a process gas outlet tube are installed symmetrically and concentrically with respect to a substrate, thereby allowing the process gas to flow uniformly, evenly and smoothly over the substrate, thereby forming a thin film uniformly over the substrate. A uniquely designed showerhead assembly provides not only reduces the volume of the reactor space, but also allows the process gases to flow uniformly, evenly and smoothly throughout the reation space area and reduces the volume of the reaction space, and the smaller volume makes it easier and fast to change the process gases for sequential and repeated process operation.

CROSS-REFERENCE TO RELATED APPLICATION DATA

This application claims priority from PCT International Application No.PCT/KR01/01333 filed Aug. 6, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plasma enhanced atomic layerdeposition (PEALD) apparatus and method of forming a thin film using thesame. Particularly, the present invention relates to a PEALD apparatusand method of forming a thin film using the same, whereby a thin film isformed to an atomic layer thickness by periodically supplyingtime-divisional (sequential) combination of process gases to a reactor,during which plasma is generated adequately and synchronously withprocess gases on top of a substrate in order to accelerate the processreaction and facilitate more efficient reaction.

2. Description of the Related Art

As semiconductor integration technologies advance, process methods fordepositing a thin film uniformly and conformally become increasinglyimportant. Here, the thin film may be an insulator or a conductor. Thinfilm deposition methods are largely categorized into two types: chemicalvapor deposition (CVD) and physical vapor deposition (PVD). In a CVD,gas phase materials generally react over the top surface of a substrateheated to a temperature of 100–1,000 degree. C., whereby a compoundproduced as a result of such reaction is deposited on the top surface ofthe substrate. On the other hand, the PVD method such as sputteringdeposition or simply sputtering, are widely used, whereby the processtakes place also in a vacuum state in a reactor. When a gas such as Argas as an example is supplied to a reactor, the Ar gas becomespositively ionized by a plasma and attracted to a target located insidethe reactor. As the ionized Ar atoms get closer to the target, they getaccelerated further and as the ionized and accelerated Ar atoms strikethe target, the material of the target is scattered and deposited on thesurface of a substrate, wherein the material of the target is depositedon the surface of a substrate without a chemical or structural change.

The advantage of a PVD is to make it possible to deposit an alloy or aninsulator. Nonetheless the less CVD is more widely used since CVD hasadvantages over PVD, causing less damage to substrates on which a thinfilm is deposited, offering low thin film deposition cost, andcapability of thin film deposition.

However, as the density of semiconductor devices recently continues toincrease from micrometers to nanometers, conventional CVD methods do notperform satisfactorily in forming a thin film uniformly in thickness innano scale on a substrate or achieving an excellent step coverage. Inparticular, in case of high aspect ratio, in turn large step difference,such as contact holes, vias or trenches, of small dimensions thanmicrometer (micron), difficulty exists in forming a thin film havinguniform composition regardless of high aspect ratios in various patternssuch as contacts, via holes or trenches over the entire surface of thesubstrate.

Unlike conventional CVD method, where all process gases aresimultaneously supplied (in flow) or removed (outflow). In ALD methodeach atomic layer of thin film is formed by repeating the thin filmdeposition process by avoiding the direct contact of process gases onthe substrate surface and by replacing the process gases rapidly andsequentially within the process gas cycles. This new method of formingthin films is being developed and used.

When the aforementioned atomic Layer Deposition method is used, thedeposition takes place only by the material that is adsorbed on thesurface of a substrate, i.e., only by the chemical molecule thatcontains the elements for forming a thin film, whereby a thin film isformed uniformly over the entire surface of a substrate regardless ofthe quantity of the process gas because the amount of adsorption is onthe surface of a substrate is limited by the thickness of a mono layer.Therefore, a uniform thickness of thin film can be formed regardless ofthe location of the areas of high aspect ratio, in turn, large stepdifference, and even a thin film with the level of thickness of severalnano meters can be formed, and also the thickness of the thin film canbe controlled by adjusting the time-divisional combinations of the stepsof the formation processes. Furthermore, it is possible to control thethickness of the thin film being formed because the thickness of thethin film formed by deposition during the process gas supply cycle isalmost constant.

According to the conventional ALD method described above, in order toavoid mixing of gas materials in a gas phase supplied to a reactor in atime-division mode, remaining deposition gas or reaction gas moleculesexcluding those adsorbed on the substrate surface among deposition gasor reaction gas supplied to the reactor should be removed, for which theprocesses of vacuum evacuating the deposition gas or reactant gas fromthe reactor for several seconds or purging those gas out of the reactorby feeding an inert gas such as Argon gas, must be included in the cycleof gas supply and evacuation thereof.

Accordingly, use of a conventional CVD equipment, in which supply andremoval of process gases cannot be made at a fast rate at the speedwithin several seconds, may increase the deposition time required forobtaining a thin film of a desired thickness because the longer timeneeded for replacing the process gas. Increased deposition time reducesthe number of wafers to be processed per unit time by one equipment,thereby increasing the processing cost. As the deposition timeincreases, the number of wafers that can be processed with eachequipment decreases, thereby, the cost of process increases. Therefore,it is necessary to reduce the deposition time in order to utilize ALDmethods for producing semiconductor products using ALD methods.

FIGS. 1 a and 1 b show two schematic structure of a conventionalchemical vapor deposition apparatus.

Referring to FIG. 1 a as a first prior art of an Atomic LayerDeposition(ALD), at the top part of a reactor 100 gas inlet tube 120that supplies process gases including deposition gas, reactant gas,purge gas is located, and on the side of the reactor 100, a gas outlettube 122 for discharging the process gases from the reactor 100 islocated. Inside the reactor 100, a substrate carrier 116 is located onwhich a substrate 110 is loaded. Inside the reactor 100, a showerhead112 is located and at the top and in the middle of the showerhead 112,the process gas inlet tube 120 is connected. In the lower part of thereactor 100, a substrate carrier driver 118 is mounted. This substratecarrier driver 118 moves the substrate carrier 116 up and down in orderto load and unload a substrate onto and out of the substrate carrier116. This substrate carrier 116 is linked to the substrate carrierdriver 118.

The process gas inside the reaction chamber 114 travels through thespace between the reactor 100 and the substrate carrier 116 and thenexhausted through the gas outlet tube 122. In this prior art, the gasoutlet tube 122 and the gas inlet tube 120 are arranged asymmetricallywith respect to the substrate 110, that is, the gas flow is imbalanced,thereby the flow of the process gas is biased towards the gas outlettube 122.

Therefore, when a thin film is deposited on a substrate 110, if the flowof process gas is shifted forwards one side within the reaction chamber114, the process gas is supplied unevenly over a substrate 110, therebythere is a tendency of forming a thinner film over a substrate 110 wherethere is less supply of process gas.

Accordingly, in order to minimize the imbalanced flow of process gas inthe reactor 100, either the gas outlet tube must be preferably movedaway from the substrate 110 or a means of even flow of process gas overthe substrate 110 or the outflow tube 122 must preferably be relocatedin such a way that the condition of flow of process gas over thesubstrate 110 is satisfied. However, the gas outlet tube 122 isrelocated away from the substrate 110, the volume of the reactionchamber 114 increases, thereby the process cost increases due to thefact that the amount of gas for the same process step increases, andfurthermore there is a difficulty of increased process time forsupplying and removing gases or replacing process gases for the processof sequentially supplying various types of process gases. Therefore, theprocess time increases for processing ALD(Atomic Layer Deposition)method.

Further, in the example of this prior art, the substrate carrier 116 andthe substrate carrier driver 118 are exposed to the process gas that isexhausted through the gas outlet tube 122, thereby undesirable thin filmis deposited on or around the aforementioned parts. Later suchundesirably deposited layer of thin film becomes not only the cause ofundesirable micro-particles(contaminants) detrimental to the subsequentprocessing steps, but also the cause of potentially erratic operation ofthe parts inside the reaction chamber 114.

The second prior art shown in FIG. 1 b, is to solve the problems in thefirst prior art shown in FIG. 1 a as described above, and in FIG. 1 b,the gas outlet tube 222 is positioned in the lower part of the middle ofthe reactor 200 so that the gas inlet tube 220 and the gas outlet tube222 are arranged symmetrically. Specifically, referring to the schematicdrawing of the second prior art as shown in FIG. 1 b, unlike in FIG. 1a, the flow of process gas in the reaction chamber 214 is symmetric andeven over the substrate 210, but the substrate carrier 216 and thesubstrate carrier drive 218 are still exposed to the process gas. Also,the volume of the reaction chamber can not be reduced significantlyenough, in order to reduce the processing time for ALD processes. Thisis because the substrate carrier driver 218 still requires a certainminimum volume for moving the substrate carrier for normal operation ofloading and unloading a substrate.

FIG. 2 is a timing sequence illustrating the process of conventional ALDprocess method. The vertical axis represents the process gas volume andthe horizontal axis represents the processing time.

Referring to FIG. 2, the ALD process cycle is in the sequence of supplyof first source gas 310→purge 312→supply of second source gas 314→purge312. At the purge stage, the source gas supplied to the reaction chamberis removed either by evacuating the reaction chamber using a vacuum pumpor by feeding an inert purge gas into the reaction chamber.

In the conventional ALD process, in case that the source gases reactwith each other easily, even a small amount of residual source gases maycause the undesirable generation of particles(contaminants), andtherefore, it may be necessary to extend the time of purging. On theother hard, in case that the source gases react slowly, and as a resultthe processing time becomes longer, then the time for supplying thesource gases may have to be lengthened, thereby the deposition timebecomes longer.

Therefore, in order to solve these problems described above, theinvertors of the present invention recently disclosed in KR0273473 aplasma enhanced atomic layer deposition method(PEALD), that improves thereactivity, reduces the purging time and thus improves the depositionrate, and as a result, improves the productivity of the depositionapparatus.

The difference between the plasma enhanced atomic layer depositionmethod and the aforementioned conventional ALD is a faster depositionrate even though source gases with low reactivity are used.

In the conventional ALD method aforementioned, when the source gaseswith low reaction rate are used, there is a slow reaction on thesubstrate, thereby, there may be a problem of lack of deposition of thinfilm.

However, the plasma enhanced atomic layer deposition method disclosedhere increases the deposition reaction rate by generating radicals andions with high reactivity by using a plasma, thereby these radicals andions actively participate in the reaction process.

As an example of an apparatus that is suitable for processing usingconventional ALD method, especially, the plasma enhanced ALD method hasbeen disclosed in the patent application KR99-23078, “ChemicalDeposition Reactor”, which invention reduces the volume of the reactionchamber, provides a means of even flow of the source gases when thesegases supplied, and removed through the gas inlet tube and the gasoutlet tube, respectively, flows over the substrate, and provided ameans of generating a plasma. However, when this apparatus is used forforming a conductive thin film, a plasma may not be generated because ofthe fact that two electrodes used for applying RF power for plasmageneration are electrically shorted due to the formation of a conductivethin film, and therefore, a conductive thin film may not be formed byusing this apparatus along with the plasma enhanced atomic layerdeposition method disclosed in the present invention.

SUMMARY OF THE INVENTION

The object of the present invention is to construct a reactor withinwhich the process gases are replaced in a short period of time in orderto process atomic layer deposition method, and also within which aplasma is generated over the surface area of a substrate, thereby evenif a conductive thin layers are deposited, without causing theaforementioned electrical short in the reactor, and at the same time theatomic layer deposition process can easily be carried out, and is toprovide an apparatus for forming a high quality thin film by using theplasma enhanced atomic layer deposition method according to the presentinvention.

Another object of the present invention is to provide a method offorming efficiently a good quality of thin film, even if the sourcegases do not react with each other easily or the reactivity is veryweak, by using a plasma enhanced atomic layer deposition apparatusaccording to the present invention.

According to the present invention, the plasma enhanced atomic layerdeposition apparatus is equipped with a substrate carrier that supportsa substrate, a reactor within which said substrate carrier is mounted,within this reactor a showerhead that supplies source gases uniformly onthe surface of a substrate, gas inlet and outlet tubes that feeds andremoves gases into and out of a reactor, and a plasma generating unitthat accelerates thin film deposition process in the reactor into whichthis plasma generating unit is mounted. In addition, a process gassupply and purge system that supplies and removes process gases througha gas inlet and gas outlet tubes in a combination of time-divisionalmanner, is installed in the PEALD tool, and finally a controller thatcontrol and manages the entire system is also installed.

According to the present invention, more specifically, the process gassupply and removal system of the plasma enhanced atomic layer depositionapparatus makes it possible to supply (process gas inlet) and remove(process gas outlet) into and out of a reactor in short time interval insuch a way that the gas supply and removal process take place in afashion of a combination of time-divisional sequence, and also thecontroller of said apparatus controls the reactor, the plasma generationunit inside of the reactor, the process gas supply and removal systemincluding a gas evacuation vacuum pump and the deposition chamber system(reactor system).

According to the present invention, a process gas inlet tube and aprocess gas outlet tube are installed symmetrically and concentricallywith respect to substrate inside the reactor in order to supply anddistribute the process gas uniformly over the substrate within thereaction space. To achieve this, the process gas inlet tube and theprocess gas outlet tube are placed centrally with respect to thesubstrate and in the peripheral area, respectively, in the reactor. Inthe embodiment described later, both gas inlet and gas outlet tubes areplaced at the center of the upper part of the reactor and for this a setof concentrically structured two tubes is used. However, as an example,the process gas inlet tube may be placed around the peripheral area ofthe substrate. At the central location of the reactor, a showerhead ismounted for an even distribution of the process gas, and according tothe present invention this showerhead has a shape of the open end of ahorn. This horn-shaped showerhead can have many different shapes, forexample, the edge of said horn may have an S-shape. However, thecommonality in the horn-shaped showerhead is that the shape of the innersurface of the showerhead is streamlined-shape so that the process gassupplied though a gas inlet tube, the process gas is distributed evenlyand uniformly along the inner surface of the showerhead. In the lowerpart of this showerhead, a grid with many holes or grids for dispersinga gas is mounted in parallel with the substrate. This grid disperses theprocess gas evenly and uniformly over the surface of the substrate.

The showerhead is horn-shaped for the reason of reducing the volume thatthe process gas occupies. Another reason for using a horn-shapedshowerhead is to eliminate any corners inside the showerhead, in orderto prevent the process gas from being trapped by and around theseundesirable corners, thereby the flow of the process gas is curledaround these corners, and as a result, these corners interfere with theuniform flow of the process gas. The horn-shaped showerhead helps theprocess gas flow uniformly, evenly and is smoothly.

According to the present invention, a volume adjusting horn and a gasdispersion perforated grid within the showerhead are the major partsforming a (+) electrode, the remaining metallic parts form a (−)electrode. Therefore, the plasma is generated only in the “reactionchamber” in the reaction space. In other words, the plasma is generatedbetween the showerhead and the substrate carrier, and practically on thesurface of the substrate.

The showerhead insulating wall made of non-conducting material of theshower head unit, and fixes the showerhead to the reactor. In order toprevent the formation of a conducting film on the surface of theshowerhead, a barrier layer of plasma generation is provided between theinsulating wall of the showerhead and the reactor wall. Formation of aconducting layer on the outer face of the insulating wall of theshowerhead is prevented by blocking the flow of the process gas throughthe slits between the barrier layer of plasma generation and theinsulating wall of the showerhead by continuously pushing an inert gasthrough said “slits” between said barrier layer of plasma generation andsaid insulating layer of said showerhead.

Radio frequency connection terminals are connected to the shower headfor supplying RF (radio frequency) power to it.

Said radio frequency connection terminal is made of a tube-shapedmetallic material and when desired RF power is supplied throughterminal, an inert gas can be supplied through the space between theshowerhead insulating wall and the barrier wall of plasma generation.

According to the present invention, the process gas inlet tube isconnected to said showerhead through a micro-feeding tube assembly madeof insulating materials. This micro-feeding tube assembly has more thanone micro-tube in the middle of it, thereby said process gas is fed tothe showerhead, but the plasma is blocked from reversed flow of reactiongas that may remain in the reactor or may be supplied to the reactor andalso blocked from any leakage. The length of this micro-feed tube andthe diameter of the micro-tuber are determined in such a way that theplasma does not leak.

According to the present invention, the substrate carrier is located inthe lower part of the reactor and between the substrate carrier and thereactor wall there is a flat thin washer-like gas sealer ring for notonly preventing the leakage or outflow of the process gas out of thereaction space, but also blocking the unnecessary film formation on thesurface of the substrate carrier by blocking the contact of the processgas and the substrate carrier. Formation of unnecessary thin film doesnot occur even when the plasma is generated because the process gas doesnot contact with the substrate carrier. Also, according to the presentinvention, said gas sealer ring plays a key role of preventing theoperational hindrance of the substrate carrier driver ever if theprocess gas is leaked into the external operational space of thesubstrate carrier, which space is filled with an inert gas such as Ar,thereby unnecessary metallic film is formed on the substrate carriersupport and driver mechanisms.

According to the present invention, the substrate carrier is supportedby a center support pin, center shaft, a plurality of driver shafts.Also, the substrate carrier moves up and down by a pneumatic cylinderlinked to the driver shafts, thereby a substrate can be loaded onto andunloaded from the substrate carrier. Those parts described above areenclosed and sealed in the reactor body, and the operational space ofthe substrate carrier is filled with an inert gas such as Argon(Ar) sothat it blocks any gas leaks as well as formation of unnecessarymetallic film is blocked.

According to the present invention, as aforementioned, the reactor isenclosed by the reactor body an inert gas is fed through the inert gasinlet tube and is removed through the inert gas outlet tube, where theinert gas inlet and outlet tubes are installed in the reactor body.Here, the pneumatic cylinders are mounted outside of the reactor body.

According to the present invention, heaters are installed in the reactorwalls and underneath the substrate carrier, thereby the substrate andthe reactor body can be heated to a desired level, if necessary. Thereactor body is electrically grounded, and through the driver shafts,the substrate carrier is also grounded. Also, the reactor walls areconnected to the reactor body, and therefore, the reactor walls areelectrically grounded.

According to another aspect of the present invention, a method offorming thin films by using plasma activation even when a source gascontaining metallic elements does not react in a reactor, process gasincludes this source gas(or deposition gas) and a purge gas, isdisclosed. A substrate is loaded on the substrate carrier in a reactor.

Through a gas inlet tube, said source gas is fed into the reactor,supply of said deposition gas(or source gas) is ceased, and while saidpurge gas is fed into the reactor, plasma is generated in order toactivate the film deposition reaction. According to the presentinvention, said method comprises the steps of feeding a source gas intoa reactor, feeding a purge gas, generating plasma, and repeating saidsteps for a specified number of times in order to deposit a film to adesired thickness, thereby, forming a conducting layer of a thin film.

At the lower end of said gas inlet tube, micro-feeding tube assembly inwhich a plurality of fine and small micro-tubes are arranged inparallel, and said process gases are fed through said gas inlet tube andthen through said micro-feeding tube assembly and finally into theshowerhead assembly area inside the reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings in which:

FIGS. 1 a and 1 b are conceptual schematic drawings of conventionalchemical vapor deposition apparatus.

FIG. 2 is a timing diagram for a thin film formation process using aconventional chemical vapor deposition apparatus showing a sequence ofthe process gas supply and removal.

FIG. 3 is a schematic drawing of the cross-section of plasma enhancedatomic layer deposition apparatus according to the present invention

FIG. 4 is a timing diagram for a thin film formation process using anplasma enhanced vapor deposition apparatus according to the presentinvention showing a sequence of the process gas supply and removal aswell as the plasma generation.

FIG. 5 is a flow chart for the process of forming a conducting thin filmby using a plasma enhanced atomic layer deposition apparatus accordingto the present invention, showing the sequence of process gas supply andremoval as well as plasma generation.

DETAILED DESCRIPTION OF THE INVENTION

The detailed description of the present invention aforedescribed, willbecome clear through this Best Mode for Carrying Out the Invention.

FIG. 3 is a cross-sectional schematic diagram of a plasma enhancedatomic layer deposition apparatus according to the Best Mode of thepresent invention.

Referring to FIG. 3, a heater is installed at the bottom part of thesubstrate carrier 560 so that it can control the temperature of thesubstrate 556 or the reaction space 554 as necessary. In addition, aheater 604 installed on the reactor walls 522 may be if necessary usedfor increasing the temperature of the reactor which is the inside of thereactor wall.

At the upper part of the reactor wall 522 made of an alloy, a dualorifice tube assembly 516 and at the lower part of the reactor wall 522,there is a substrate carrier 560. The substrate carrier 560 and thereactor wall 522 define the inner part of the reactor. A gas sealer ring558 is located between the top surface of the outer ring of thesubstrate carrier 560 and the bottom end of the reactor wall 522, andthis gas sealer ring 558 shaped as a thin flat washer-like with an innerside hovelled and outer side-square edged ring seals between thesubstrate carrier 560 and the reactor wall 522 as well as covers the topsurface of the outer ring area of the substrate carrier 560. This gassealer ring 558 prevents the process gas from leaking as well asprotects the substrate carrier 560 from being exposed to process gases.The gas inlet tube 510 is mounted as a part of dual orifice tubeassembly 516 in the upper part of the reactor wall 522. The process gastravels in the direction of arrows through the micro-feeding tubeassembly 536 and then into the inner part 552 of the showerheadassembly. The outer tube 514 of the dual orifice tube assembly 516 is apassage way of flowing for the process gas, and the inner tube 510 ofthe dual orifice tube assembly 516, in other words, the gas inlet tube510 is the inlet entrance for the process gas. The process 552 gas flowsin the direction of indicated by arrows inside of the inner tube 510.

The showerhead assembly (540, 542) comprises a volume adjusting horn 540and a gas dispersion perforated grid 542. The shape of the volumeadjusting horn 540 allows the process gas to distribute uniformly,evenly and smoothly over the substrate 556, and at the same time,minimizes the volume of the inner part of the showerhead 552. Morespecifically, the reason for making the shape of the showerhead 540 ason open end of a horn is to reduce the volume of the inner part of theshowerhead 552, and such a shape reduces the curling effect of theprocess gas flow, and thereby the process gas is distributed uniformlyand evenly, otherwise any corners that may exist in the inner part ofthe showerhead 552 would cause trapping of the process gas and, therebyaround these corners curling phenomenon may occur.

Furthermore, the shape of a horn itself makes the flow of the processgas even and uniform. At the bottom part of the volume adjusting horn540, a gas dispersion perforated grid 542 is mounted and this makes theflow of the process gas even more uniform, thereby it allows the processgas to he distributed uniformly over the top surface of a substrate 556.The showerhead assembly (540, 542) and the bottom end of the gas inlettube 510 are connected through a micro-feeding tube assembly 536, andtherefore, the process gas enters into the gas inlet tube 510 and flowsin the direction of arrows indicated, and continue to flow through themicro-feeding tube assembly 536 and then to the inner part 552 of theshowerhead assembly.

As described above, the shape of the volume adjusting horn 540 isdesigned to minimize its volume for proper processing of a substrate,and yet to let a process gas to flow smoothly and evenly over asubstrate 556 as well as to make the removal of a process gas andfilling a incoming process gas easily and fast. More specifically,during a sequential supply of process gases, the possibility of thevapor state reaction between a new process gas and the residual gas ofthe previous supply cycle accumulated and remained unnecessarily in theinner part of the showerhead 552. The dual orifice tube assembly 516 is,as described previously, connected to the inlet opening of the reactorwall 522 and the outer tube of the dual orifice tube assembly 516 isconnected to a vacuum pump 598 through a gas outlet tube 518. Therefore,the process gas entered into the reaction space 554 by being dispersedevenly through the gas dispersion perforated grid(or showerhead grid)542 travels through the gap 526 (passage of removal gas indicated byarrows) between the reactor wall 522 and the plasma generation barrier528, and then through the gas outlet tube 518, and then finally to thevacuum pump 598.

In FIG. 3, the arrows indicate the direction of the flow of a processgas. The reactor wall 522 may be heated by using a heater 604 asnecessary. The radio frequency connection terminal 566 is made of ametallic tube for receiving a radio frequency power from outside and aninsulation tube 568 made of an insulating material, and this terminal566 is connected electrically to both volume adjusting horn 540 and thegas dispersion perforated grid 542 as a plus (+) polarity. The radiofrequency connection terminal 566, shielded with an insulating tube 568is connected to the volume adjusting horn 540 through the reactor body600, the reactor wall 522, the plasma generation barrier 528 and theshowerhead insulation wall 538. Because of the insulating tube 568, theradio frequency connection terminal 566 is electrically insulated formthe reactor body 600, reactor wall 522 and the plasma generation barrierwall 528, whereas the radio frequency connection terminal 566 which is aconductor, is electrically connected only to the volume adjusting horn540.

On the other hand, the showerhead insulating wall 538 is electricallyinsulated from the radio frequency terminal 566 because the showerheadinsulating wall 538 is made of an insulating material.

On the other hand, the gas inlet tube 510(on an inner tube) is aconductor, and because the micro-feeding tube assembly 536 is made of aninsulating material, the showerhead assembly 540, 542 is electricallyinsulated from the reactor wall 522 as well as the reactor body 600. Andthe substrate 556 as well as the substrate carrier 560 is electricallyconnected to ground 594 through the driver shaft 580 and the reactorbody 600. Therefore, when radio frequency power is applied by using anRF generator (not shown), plasma is generated between the showerheadassembly 540, 542 as a positive (+) polarity and the substrate 556 aswell as the substrate carrier 560 as a negative (−) polarity. Then, athin film is formed on the substrate 556 due to the source gas used andactivated by the plasma generated. Here, the plasma is generated only inthe reaction space 554 between the gas dispersion perforated grid 542and the substrate 556 as well as the substrate carrier 560. According tothe present invention, the plasma generation barrier wall 528 isinstalled between the showerhead insulation wall 538 and the reactorwall 522 in order to prevent any electrical short between the showerheadassembly 540, 542 and any metallic part within the reactor such as thereactor wall 522 due to a formation of a conductive thin film on thesurface of the showerhead insulation wall 538 which is used for mountingthe showerhead assembly 540, 542 to the reactor body 600. Here, thereare two key aspects of installing a plasma generation barrier wall 528.First, the plasma generation barrier wall 528 is electrically connectedto ground 594 through the gas inlet tube 510 and the reactor body 600.Therefore, plasma is not generated in the passage of removal gas 526between the plasma generation barrier wall 528 and the reactor wall 522,thereby a conductive thin film is not formed, and therefore, thispassage 526 is used as a passage for process gases. Second, the passageof inert gas 544 between the showerhead insulation wall 538 and theplasma generation barrier wall 528 allows plasma to generate even if inthe lower tip end part of the showerhead insulation wall 538 near thesubstrate carrier 560 has a conductive thin film is formed, and also bysupplying an inert gas continuously through the narrow passage of inertgas 544, plasma generation near the end part of the passage of inert gas544, and formation of a conductive thin film is blocked, and thereby,this prevents an electrical short between the showerhead assembly 540,542 and ground 594 from occurring.

As described above, by supplying an inert gas such as Argon(Ar) throughthe inner tube 564 of the radio frequency connection terminal 566 andthen through the narrow passage of inert gas 544 between the showerheadinsulation wall 538 and the plasma generation barrier wall 528, and asthe inert gas continue to flow, as indicated by arrows, through the gapbetween the showerhead insulation wall 538 and the plasma generationbarrier wall 528 and then around the end part of the passage of inertgas 544 and then continues to flow through the gap between the plasmageneration barrier wall 528 and the reactor wall 522, and theneventually the inert gas travels through the gas outlet tube 518 and isthen exhausted through the vacuum pump 598. This inert gas is suppliedcontinuously even during the thin film deposition process, periodthereby formation of a conductive thin film on the surface of theshowerhead insulation wall 538 is prevented by blocking the exposure ofthe top and side parts of the showerhead insulation wall 538 to processgas.

On the other hand, by constructing the micro-feeding tube assembly 536with a plural of small and fine tubes with small in diameter, a plasmageneration inside the micro-feeding tube assembly 536, thereby formationof a thin conductive film inside of the micro-feeding tube assembly 536is prevented.

According to the present invention, the invention comprises four(4)significant inventive parts. First one is the shape of the volumeadjusting horn 540 of the showerhead assembly 540, 542, the second isthe structure of the micro-feeding tube assembly 536, the third is thearrangement of a thin gap provided between the showerhead insulationwall 538 so that an inert gas such as Argon(Ar) is continuouslysupplied, and the fourth is an efficient way of structuring a plasmageneration unit by arranging and using a radio frequency powerconnection terminal 566 made of a conducting tube and an insulating tube568 made of an electrically insulating material.

On the other hand, since it is possible that plasma generation may takeplace due to the potential difference between the gas inlet tube 510 andthe showerhead assembly(540, 542), this undesirable presence of plasmamight cause formation of conductive thin film on the inner surface ofthe part where the showerhead insulation wall 538 and the showerheadassembly 540, 542 are connected (This is the part where themicro-feeding tube assembly 536 is located), thereby, the conductivethin film formed around the centrally located hole in the middle of theshowerhead insulation wall 538 may cause on electrical short between theshowerhead assembly 540, 542 and the gas inlet tube 510. Therefore, inorder to suppress undesired plasma generation in the neighborhood of theaforementioned micro-feeding tube assembly 536, said micro-feeding tubeassembly 536 structured with a plural of tubes with small in diameter,in parallel, is assembled to connect the showerhead assembly 540, 542and the gas inlet tube so that the micro-feeding tube assembly 536suppresses the plasma generation while the inert gas flows steadily.Aforementioned micro-feeding tube assembly 536 is made of insulatingmaterials. The size of the diameter of the small tubes in themicro-feeding tube assembly 536 is chosen in such a way that the size issmall enough so that plasma generation does not occur, yet an adequateamount of gas flows through steadily. In the present best mode for thepresent invention, it was found adequate that the over-all diameter ofthe micro-feeding tube assembly is about 6 mm and its length is about 20mm and the diameter of the small tubes is about 0.6 mm and eight(8) ofthem altogether are used to construct a micro-feeding tube assembly 536.

Instead of using a micro-feeding tube assembly 536 made of insulatingmaterial, for connecting the gas inlet tube 510 and the showerheadassembly 540, 542, a set of long tubes sufficiently longer than thedistance between the gas dispersion perforated grid 542 and thesubstrate 556 so that the occurrence of plasma generation inside thesetubes may be prevented. However, to do this, the upper part of thethickness of the showerhead insulation wall 538 must be made thicker inorder to accommodate the extra length of the gas dispersing perforatedgrid 542 as well as other parts of the reactor assembly must besignificantly enlarged, thereby the cost and material for constructingsuch a part increases.

In a small space, the frequency of collisions between the electrons andgas atoms or molecules while the electrons moving towards electrodesoften being accelerated due to the electric and magnetic fields. Inorder to maintain the state of plasma, the electrons sufficientlyaccelerated in a given electric and magnetic fields collide with theneutral gas particles and such collisions ionize the atoms andmolecules, thereby release the electrons bound in such atoms andmolecules, and in turn, these electrons are sufficiently accelerated bythe fields, and then collide with other neutral gas particles, therebyrelease the electrons found in other atoms and molecules, and thisprocess must repeat by itself, again, in order for the state of plasmato be maintained. However, in general, in a small space the electronscollide with solids and loose their energy before such electrons gainsufficient energy for releasing other electrons from neutral gasparticles, thereby the process of ionizing the neutral gas particle doesnot progress efficiently, and as a result, the plasma generation processis suppressed in a small space.

Furthermore, referring to FIG. 3, a potential difference between thereactor wall 522 and the showerhead insulation wall 538 may exist andtherefore a plasma state may be generated here, and as a result, on theinside surface of the reactor wall 522 and the outside surface of theshowerhead insulation wall 538, a conducting thin film may be formed dueto the reaction of the process gas occurring while such process gas ispassing through the reactor space 554, the reactor wall 552, and thenthe showerhead insulation wall 538. The conducting thin film formed onthe outer surface of the showerhead insulation wall 538 may cause anelectrical short between the showerhead assembly 540, 542 and thereactor wall 522, which is connected to ground.

In order to remedy the problem described above, according to the presentinvention, a plasma generation barrier wall 528 is constructed betweenthe reactor wall 522 and the showerhead insulation wall 538, and alsoconnect electrically with the reactor wall 522 through the gas inlettube 510(inner tube), the plasma generation does not take place due tothe fact that there is no potential difference between the plasmageneration barrier wall 528 and the reactor wall 522. If thedistance(space) between the plasma generation barrier wall 528 and theshowerhead insulation wall 538 is reduced, the plasma generation in thisneighborhood can be suppressed. In this case, the plasma generationtakes place mainly in the relatively spacious reaction space 554 betweenthe gas dispersion perforated grid 542 and the substrate 556 where theshowerhead assembly 540, 542 to which radio frequency power is appliedwith respect to grounded. Also, by supplying an inert gas such asArgon(Ar) continuously during the film formation period through the gaps544, 548, 526 between the plasma generation barrier wall 528 and theshowerhead insulation wall 538 in the direction of arrows, undesiredflow of process gases through the end part of the passage of inert gas548 as well as the passage of inert gas 544 can be prevented. Thenecessary inert gas for above step is supplied through a tube-shapedradio frequency power connection terminal 566. The inert gas is suppliedthrough the hole at the center of the radio frequency power connectionterminal 566 and then through the hole 564 in the tube, and then throughthe gaps between the showerhead insulation wall 538 and the plasmageneration barrier wall 528 as indicated by arrows. The inert gas thentravels the gaps and passage ways 620, 624, 626, 628 and to the passageof inert gas 544 and then continue to flow following the arrows. Here,it is desirable to provide a set of passage ways and buffering spacessuch as 620, 624, 626 and 628 for proper flow of an inert gas. Also,such passage ways and buffering spaces are preferably arranged so that aproper, adequate, and smooth flow of the inert gas is achieved. Sucharrangement preferably provides a uniform and even flow of the inert gasthrough out the inert gas passage ways as indicated by arrows even ifthe location of the radio frequency connection terminal 566 is locatedoff centered, as shown in the FIG. 3. According to the best mode of thepresent invention, for the gap size of the passage of inert gas 544 is0.4 mm and the gap size of the end part of the passage of inert gas 548is 0.4 mm, respectively, and the outside diameter of the showerheadinsulation wall 538 is 210 mm for the 200 mm wafer, and a gas issupplied at the flow rate of 20 sccm, the flow velocity of the gas atthe gaps of the passage of inert gas 544 and the end part of the passageof inert gas 548, respectively, is 19 mm/s at the temperature of 25° C.and the pressure of 5 Torr. As the temperature increases, the flowvelocity increases.

More specifically, referring to FIG. 3, When a inert gas such asArgon(Ar) is supplied by using an MFC(Mass flow controller)(not shown)through the inert gas inlet tube 566 which is called the radio frequencyconnection terminal 566 previously, where ibis terminal 566 is made of aconducting material, the inert gas is forcibly supplied through theinert gas inlet tube 566 and flows, as indicated by arrows, through thefirst reservoir ring 620, the inert gas passage way 622, the secondreservoir ring 624, the third reservoir ring 626 and the fourthreservoir ring 628, and then through the passage of inert gas which isthe gap between the showerhead insulation wall 538 and the plasmageneration barrier wall 528, and then continue to flow following thearrows, and eventually flows through the end part of the passage ofinert gas 548 which is the bottom part of the showerhead insulation wall538 and the plasma generation barrier wall 528, respectively, andfinally joins with the process gas and this mixed gas flows through thepassage of removal gas 526 which is the gap between the plasmageneration barrier wall 528 and the reactor wall 522, and follow thedirection of flow and then through the gas outlet tube 518, and thenexhausted by the vacuum pump 598.

During this gas flow process, the flow of the inert gas through the endpart of the passage of inert gas 548 blocks backflow of the process gasinside of the reaction space 554 flowing through the gap of the passageof inert gas 544 which is the gap between the showerhead insulation wall538 and the plasma generation barrier wall 528 and flowing backwardsagainst the flow of inert gas into the passage of inert gas 544, andtherefore, when a process gas containing metallic material is used, noundesirable conducting thin film is formed inside of the passage ofinert gas 544, particularly around the end part of the passage of inertgas 548, and as a result, it does not create a problem of an electricalshort. This prolongs the life of the usage of the surrounding areas ofthe reaction space 554.

A conducting thin film is formed only in the areas where a process gasis supplied and present and the plasma generation occurs. This meansthat no conductive thin film is formed between the plasma generationbarrier wall 528 and the reactor wall 522 because no plasma isgenerated, and that no conductive thin film is formed between the plasmageneration barrier wall 528 and the showerhead insulation wall 538because no process gas is supplied and present. Consequently, aconducting thin film is formed only within the reaction space 554, wherea substrate 556 is located and no conducting thin film is formed outsidethe reaction space 544, and therefore, an electrical short is blockedeven if the process of formation of a conducting thin film is repeated.

According to the present invention, a reactor body 600 includes thereactor wall 522 along with the elements installed inside including asubstrate carries 560, an inert gas inlet tube 590 and an inert gasoutlet tube 592 equipped with an on-off valves for gases, respectively,where the exact location of these gas inlet and outlet tubes is notsignificant.

The purpose of using this secondary inert gas covering most of thereactor parts is to reduce the gas leakage by maintaining the pressurelevel of the secondary inert gas as such. More will be described later.The radio frequency connection terminal 566 is connected to theshowerhead assembly 540,542 though the reactor body 600 as well as thereactor wall 522, and this installation process provides electricalinsulation of the radio frequency connection terminal from the reactorbody 600 as well as the reactor wall 522. Furthermore, according to thepresent invention of the plasma enhanced atomic layer depositionapparatus, when a showerhead insulation wall 538 and a plasma generationbarrier wall 528 are constructed, a radio frequency connection terminal566 is connected to a showerhead assembly 540, 542 through a reactorbody 600, a reactor wall 522, a plasma generation barrier wall 528 andthen a showerhead insulation wall 538, and the connections are made withthe reactor body 600, the reactor wall 522 and the plasma generationbarrier wall 528 in such a way that the radio frequency connectionterminal is electrically insulated from the parts described above. Thereactor body 600 has mainly two parts of a top cover and the bottombody. As described above, leakage of inside of the reaction space 554can be prevented by maintaining the pressure of the inert gas that issupplied through the inert gas inlet tube 590 and then out through theinert gas outlet tube 592 higher than the pressure of the gas inside ofthe reaction space 554.

The substrate carrier driven assembly for driving a substrate carrier560 consists of primarily pneumatic cylinders 584, a drive shaft 580that connects the pneumatic cylinder 584 and a substrate carrier 560,and a girding plate 578 that maintains a balance among the drive shafts580. When a substrate is loaded and unloaded on or from the substratecarrier 560, the substrate carrier connected to an pneumatic cylinder584 moves downwards, so that the reactor wall 522 and the substratecarrier 560 are separated and the reaction space 554 is opened. Thistime, the center support pin 572 is connected to the center axis stopperpin 574, and this stopper pin 574 stops the downward movement at a givenheight. As the substrate 556 continues moving downward further, thesubstrate carrier is separated from the substrate 556 since it issupported by the center support pin 572 and stops by the center supportstopper pin 574, but the substrate carrier 560 continues to movedownwards as the pneumatic cylinders 584 pulls the substrate carrier 560further down. The substrate 556 stops at a given height so that a robotarm (not shown) is able to load or unload the substrate 556. The lengthsof the center support stopper pin 574 and the center support pin 572 areadjusted as necessary in order to accommodate the movements of a robotarm(not shown).

According to the present invention of the plasma enhanced atomic layerdeposition apparatus, the volume adjusting horn 540 that has a shape ofa horn makes the flow of the process gas smooth and evenly distributed,while the volume of the inside of the showerhead is minimized and thusthe exchange of the process gases are done easily and quickly, therebypotentially the unnecessary reaction between the residual gas remainedinside of the showerhead assembly 540, 542 from previous process cycleand the subsequently supplied gas is minimized. Also, by using amicro-feeding tube assembly 536 made of a plural of small tubes inparallel, the plasma generation between the showerhead assembly 540, 542and the process gas inlet tube 510 can be suppressed, and also, bysupplying an inert gas through the passage of inert gas between thegrounded plasma generation barrier wall 528 and the showerheadinsulation wall 538, a thin film is formed only in the reaction space554 between the gas dispersion perforated grid 542 and a substrate 556,but no thin film is formed on other parts where a process gas flows,thereby a conducting thin film can be formed by using the plasmaenhanced atomic layer deposition method without a problem of havingelectrical shorts. Furthermore, the process gas flows within the insideof the reactor, and does not contact with the reactor body 600.

FIG. 4 is a timing diagram related to the best mode described above byusing a plasma enhanced atomic layer deposition for illustration.

Referring to FIG. 4, the source gas 440 and the purge gas 442 aresupplied in a cycle of Tcycle in a sequence of 440→442. Here, during thepurge gas 442 supply cycle, plasma generation 446 occurs for a specifiedduration of time by applying a radio frequency power 446. A source gas440 includes a metallic element such as Titanium Tetra Chloride(TiCl₄)that is used for forming a metallic thin film, and the purge gas 442 isa gas that does not react with a deposition gas by simply mixing them,but, they reacts when activated by a plasma 446.

FIG. 5 is a flowchart of typical process steps using a plasma enhancedatomic layer deposition apparatus according to the present invention.

Referring to FIG. 5, a substrate 556 is loaded onto a substrate carrier560.(step 850). The temperature of the substrate 556 is raised to adesired deposition temperature.(step 852). A source gas 440 is suppliedto a reaction space 554.(step 854) A purge gas 442 is supplied to thereaction space 554 and remove the remaining deposition gas 440. (step860) through the radio frequency power connection terminal 566, RF poweris supplied and plasma 446 is generated in the reaction space 554 andthe purge gas 442 mixed with source gas is activated.(step 864). Theplasma 446 activates the deposition gas(source) 440 adsorbed on thesurface of the substrate 556 and a thin film is formed. Then, the RFpower is switched off. Once The RF power is disconnected, the density ofthe radicals and ions in the activated purge gas is decreaseddrastically, thereby the time required to feed the purge gas after theRF power is switched off can he reduced significantly.

This process step is repeated by the specified number of times until thethin film is formed to a desired thickness.(step 866 and repeat of steps854 through 866 as necessary). Once the deposition process is completed,the substrate 556 is cooled down (step 868), and the substrate 556 isunloaded from the reaction space 554. (step 870).

According to the present invention, a thin film can be formed using onlytwo types of gases by means of atomic layer deposition method, and thisprocess makes the process gas supply and distribution system simple aswell as the deposition process cycle time(Tcycle) can be reduced.Furthermore, according to the method of the present invention, even ifsource gas 440 and the purge gas 442 may be mixed in the areas ofreaction space 554, the gas inlet tube 510, the gas outlet tube 518 andalso near the gas exhaust area, the reaction does not take place,thereby undesirable particles are not generated.

[Experimental Embodiment 1]

Following the best mode for carrying out the present invention describedabove, a thin film using Titanium Nitride(TiN) is formed by theconducting thin film formation method in accordance with the presentinvention of the plasma enhanced atomic layer deposition method. Forthis experimental, embodiment, to supply a source gas, 160 sccm ofArgon(Ar) gas and Titanium Tetra-Chloride(TiCl₄) carried by Argon(Ar)gas of 100 sccm which passes through a source container were suppliedthrough the shower head 540 in a reactor loaded with a substrate. Forthe process of supplying a purge gas, 100 sccm of Hydrogen(H₂) gas, 60sccm of Nitrogen(N₂) gas and Argon gas of 100 sccm were fed through thereactor. Through the orifice of the radio frequency power connectionterminal 566, 20 sccm of Argon gas was supplied continuously. Thesubstrate temperature was set at 350° C., the RF power was set at 150 W,and the pressure was set at 3 Torr. The duration of the source gassupply was 0.2 second and the duration of the purge gas supply was 5.8seconds. During the period of 5.8 seconds, for the first 2.0 seconds,the RF power was in the off-state, and only the purge gas was supplied.During the next 2.0 seconds, the purge gas was supplied and at the sametime the RF power was switched on to generate plasma. During the last1.8 seconds, the RF power was switched off and at the same time only thepurge gas was supplied. By repeating this 6.0 seconds cycle, a uniformquality of Titanium Nitride thin film was obtained.

[Experimental Embodiment 2]

By using the plasma enhanced atomic layer deposition method according tothe present invention, a conductive thin film of Titanium was formed.Similarly to Experimental Embodiment 1 described above, for the sourcegas supply step, 230 sccm of Argon gas and TiCl₄(TitaniumTetra-Chloride) carried by Argon gas of 100 sccm which passes through asource container was supplied to the shower head assembly 540, 542. Forthe purge gas supply step, 100 sccm of Hydrogen(H₂) gas and 230 sccm ofArgon gas were supplied. Through the orifice of the radio frequencyconnection terminal, 20 sccm of Argon gas was supplied. The substratetemperature was set at 380° C., the RF power was set at 200 W and thepressure was set at 3 Torr. The duration of the source gas supply was0.2 second, the purge gas was supplied for 5.8 seconds. During the purgegas supply time of 5.8 seconds, for the first 2.0 seconds, the RF powerwas switched off and only the purge gas was supplied. For the next 2.0seconds, the purge gas was supplied and also the RF power was turned onto generate plasma.

By repeating these 6.0 seconds of process gas supply cycles, a Titaniumthin film of uniform quality was obtained.

As described earlier, according to the present invention of the plasmaenhanced atomic layer deposition apparatus, the horn-shaped volumeadjusting horn allows a uniform distribution and even flow of the gases,and at the same time, this shape minimizes the volume of the inside ofthe showerhead, thereby it makes the exchange of gases in the reactoreasy and fast, and thus the reaction between the incoming gas into thereactor and the residual gas remaining from the previous process cycleis minimized due to the fact that a smooth horn-shaped showerheadminimizes the amount of unnecessary residual gas staying is the reactorafter the pervious gas supply cycle. Also, the micro-feeding tubeassembly made of a plural of small tubes in parallel, potentially,suppresses the plasma generation due to the potential difference betweenthe showerhead assembly and the gas inlet tube. In addition, the forcedflow of an inert gas through the gap between the plasma generationbarrier wall and the showerhead insulation wall, makes the formation ofthin film occur only inside of the reaction space which is the spacebetween the gas dispersion perforated grid and the substrate, and sincethin film is not formed on other parts even though a process gas flows,no electrical short takes place and a conducting thin film can be formedby using the plasma enhanced atomic layer deposition method according tothe present invention. Therefore, since plasma is generated only in thereaction space between the gas dispersion perforated grid and thesubstrate, and on the other parts where the process gas flows, thedeposition of thin film is suppressed, the plasma enhanced atomic layerdeposition method according to the present invention can be used forforming conducting thin films.

Furthermore, by utilizing a dual orifice tube structure for the gasinlet tube and gas outlet tube, any biased flow of the process gasestowards the location of gas outlet tube inside the reaction space, canbe avoided, and the flow of process gases flows symmetrically andbalanced way in the reaction space, thereby uniform deposition of thinfilm is possible. Also, since the flow of the process gases can bemaintained symmetrically and concentrically with respect to thesubstrate, the showerhead assembly and the reaction space can beconstructed within a smaller volume. Therefore, for the process ofsequentially supplying various types of process gases, the exchange ofgases becomes easy and fast.

Further, by employing a doubly wrapped reactor chamber body structure,thereby the process gas flows only within the inner chamber and an inertgas flows through the outer chamber, the lower part of the substratecarrier is prevented from unnecessary thin film being deposited.

Also, according to the present invention of the plasma enhanced atomiclayer deposition method allows an efficient ways of forming thin filmeven when the process gases have vary weak reaction property.Furthermore, by using the ALD method disclosed here, within the processcycle, the purge gas supply time can be minimized, and thereby theover-all process time can be shortened. Further, according to thepresent invention, generation of undesirable particles at the exhaustend of the reactor assembly can be reduced.

The present invention described in this best mode for carrying out thepresent invention is not limited by what is described and disclosed inthis best mode section and elsewhere in this invention. Those who arefamiliar in the art should be easily able to extend the ideas and waysof implementing the present invention, and many variations are plausiblewithin the scope of the technical ideas and understandings.

1. A plasma enhanced atomic layer deposition (PEALD) apparatus fordepositing a thin film on a substrate, the apparatus comprising: asubstrate carrier for supporting a substrate; a reactor wall definingthe interior of a reactor together with said substrate carrier and saidreactor wall having an opening at the top thereof; a gas inlet tube forsupplying a gas into said reactor; a showerhead assembly to which saidgas inlet tube is connected and installed within said reactor wall anddefining a reaction space together with said substrate carrier and saidshowerhead assembly for supplying a gas to said reaction space; amicro-feeding tube assembly made of insulating materials mounted betweensaid gas inlet tube and the showerhead assembly for preventinggeneration of plasma due to potential difference between said gas inlettube and the showerhead assembly while maintaining flow of gas suppliedthrough said gas inlet tube, the micro feeding tube having a pluralityof small tubes mounted in parallel, the plurality of small tubesconfigured to suppress plasma generation therein; a gas outlet tube fordischarging a gas from the reaction space; and a radio frequency (RF)connection terminal for generating plasma.
 2. The apparatus of claim 1,wherein the plurality of tubes in the micro-feeding tube assembly eachhave a diameter and a length small enough to prevent generation ofplasma.
 3. The apparatus of claim 1, wherein the gas inlet tube isinserted into the opening at the top of the reactor wall with a diameterless than the opening of the reactor wall, and the gas outlet tube isinstalled in the opening so that the gas supplied to the reaction spacepasses through a space between the reactor wall and the showerheadassembly and is discharged through a gap between the reactor wall andthe gas inlet tube.
 4. The apparatus of claim 1, wherein the RFconnection terminal is connected to the showerhead assembly through thereactor wall, and is electrically insulated form the reactor wall. 5.The apparatus of claim 1, further comprising a reactor body having a gasinlet port and a gas outlet port that can open and shut, the reactorbody forming an outer wall surrounding a predetermined region of thereactor wall and the substrate support.
 6. The apparatus of claim 5,wherein the RF connection terminal is connected to the showerheadassembly through the reactor body and the reactor wall in order to applyRF power, and is electrically insulated from the reactor body and thereactor wall.
 7. The apparatus of claim 1, further comprising a gassealer ring covering the substrate carrier and connecting to the reactorwall in order to provide sealing of the inner part of the reactor. 8.The apparatus of claim 1, further comprising a heater installed tosurround the sidewall of the reactor wall.
 9. The apparatus of claim 1,further comprising a heater installed underneath of the substratecarrier for heating the substrate.
 10. The apparatus of claim 1, whereinthe substrate carrier moves up and down so that the substrate is loadedinto or unloaded from the reaction space.
 11. A plasma enhanced atomiclayer deposition (PEALD) apparatus for depositing a thin film on asubstrate, the apparatus comprising: a substrate carrier for supportingthe substrate; a reactor wall defining the interior of the reactortogether with the substrate carrier and the reactor wall having anopening at the top thereof; a gas inlet tube for supplying a gas intothe reactor; a showerhead assembly to which the gas inlet tube isconnected and is installed within the reactor wall for defining areaction space together with the substrate carrier and the showerheadassembly for supplying a gas to the reaction space; a showerheadinsulating wall surrounding the top part and the sides of the showerheadassembly; a plasma generation barrier wall installed between theshowerhead insulating wall and the reactor wall and having the samepotential as the reactor wall, plasma generation barrier wall having agap to the showerhead insulating wall; a gas outlet tube for discharginga gas from the reaction space; and a radio frequency (RF) connectionterminal connected to the showerhead in order to apply an RF power. 12.The apparatus of claim 11, wherein an inert gas is forced to flowthrough the gap between the plasma generation barrier wall and theshowerhead insulating wall, thereby blocking the gas supplied to thereaction space from being flown into the gap between the plasmageneration barrier wall and the showerhead insulating wall and thuspreventing formation of a conductive thin film on the outside surface ofthe showerhead insulating wall.
 13. The apparatus of claim 12, whereinthe RF connection terminal has the shape of a tube so that an inert gascan flow, into it and a gap is formed between the plasma generationbarrier wall and the showerhead insulating wall, thereby providing apassage for an inert gas.
 14. The apparatus of claim 13, furthercomprising a symmetric buffered passage ways provided by forming a setof trenches on the top part of the showerhead insulating wall or thebottom part of the plasma generation barrier wall so that the inert gassupplied through the RF connection terminal flows uniformly through thegasp between the plasma generation barrier wall and the showerheadinsulating wall.
 15. The apparatus of claim 11, wherein the RFconnection terminal is connected to the showerhead assembly through thereactor wall, the plasma generation barrier wall, and the showerheadinsulating wall, and is electrically insulated from the reactor wall aswell as the plasma generation barrier wall.
 16. The apparatus of claim11, further comprising a reactor body having a gas inlet tube and a gasoutlet tube with an on-off switch, respectively, the reactor bodyforming an outer wall surrounding a specified region of the reactor walland the substrate carrier.
 17. The apparatus of claim 16, wherein the RFconnection terminal is connected to the showerhead assembly through thereactor body, the reactor wall, the plasma generation barrier wall, andthe showerhead insulating wall in order to apply an RF power, and iselectrically insulated from the reactor body, the reactor wall, and theplasma generation barrier wall.
 18. The apparatus of claim 11, whereinthe gas inlet tube is inserted into the opening at the top of thereactor wall with a diameter less than the opening of the reactor wall,and the gas outlet tube is installed in the opening so that the gassupplied to the reaction space passes through a space (gap) between thereactor wall and the plasma generation barrier wall, and is dischargedthrough a gap between the reactor wall and the gas inlet tube.
 19. Aplasma enhanced atomic layer deposition (PEALD) apparatus for depositinga thin film on a substrate, the apparatus comprising: a substratecarrier for supporting the substrate; a reactor wall defining theinterior of reactor together with said substrate carrier and having anopening at the top thereof; a gas inlet tube for supplying a gas intosaid reactor; a showerhead assembly having a volume adjusting horn forminimizing the volume of a reaction space and for allowing smooth andeven flow of a gas; a gas outlet tube for removing gas from saidreaction space; and a radio frequency (RF) power connection terminalconnected to the showerhead assembly in order to apply RF power.
 20. Theapparatus of claim 19, further comprising a showerhead insulating wallsurrounding the top and sides of said showerhead assembly.
 21. Theapparatus of claim 19, wherein said RF power connection terminal isconnected to said volume adjusting horn through said reactor wall, andis electrically insulated from said reactor wall.
 22. The apparatus ofclaim 19, further comprising a reactor body having an inert gas inletport and an inert gas outlet port with on/off valves and surroundingreactor parts including said substrate carrier.
 23. The apparatus ofclaim 22, wherein the RF connection terminal is connected to the volumeadjusting horn through said reactor body and said reactor wall in orderto apply RF power, and is electrically insulated from said reactor bodyand said reactor wall.
 24. The apparatus of claim 19, wherein a gasinlet tube is installed in the opening at the top center of said reactorwall and a gas outlet tube is installed in the opening at the top centerof said reactor wall and a gas outlet tube is installed in the openingat the top center, concentrically outside of said gas inlet tube andflows through the interior of said reactor and then exhausted throughsaid gas outlet tube.
 25. A plasma enhanced atomic layer deposition(PEALD) apparatus for depositing a thin film on a substrate, theapparatus comprising: a substrate carrier for supporting a substrate; areactor wall defining the interior of the reactor together with saidsubstrate carrier and having an opening at the top thereof; a gas inlettube for supplying a gas into said reactor; a showerhead, assembly towhich a gas inlet is connected and installed within said reactor walldefining a reaction space together with said substrate carrier and forsupplying a gas to said reaction space; a micro-feeding tube assemblymade of insulating material disposed between the gas inlet tube and theshower head for preventing generation of plasma due to potentialdifference between the gas inlet tube and the shower head whilemaintaining the flow of gas introduced from the gas inlet tube, themicro feeding tube having a plurality of narrow tubes connected inparallel; a showerhead insulating wall surrounding the top and sides ofsaid showerhead assembly; a plasma generation barrier wall installedwith a gap between said showerhead insulating wall and said reactor walland having no potential difference with respect to said reactor wall; agas outlet tube for removing a gas from said reaction space; and a radiofrequency (RF) power connection terminal connected to the showerheadassembly for applying RF power.
 26. The apparatus of claim 25, whereinthe showerhead assembly includes a gas dispersion perforated grid and avolume adjusting horn connected to a micro-feeding tube assembly througha hole at the center of said volume adjusting horn.
 27. The apparatus ofclaim 25, wherein each of the plurality of the small tubes of themicro-feeding tube assembly has a diameter small enough to preventplasma generation.
 28. The apparatus of claim 25, wherein an inert gasforced to flow through the gap between the plasma generation barrierwall and the showerhead insulting wall, thereby blocking the gassupplied to the reaction space from being flow into the gap between theplasma generation barrier wall and the showerhead insulating wall andthus preventing formation of a conductive thin film on the outsidesurface of the showerhead insulating wall.
 29. The apparatus of claim28, wherein the RF connection terminal has the shape of a tube so thatan inert gas can flow, into it and a gap is formed between the plasmageneration barrier wall and the showerhead insulating wall, therebyproviding a passage for an inert gas.
 30. The apparatus of claim 29,further comprising a symmetric buffered passage ways provided by forminga set of trenches on the top part of the showerhead insulating wall orthe bottom part of the plasma generation barrier wall so that the inertgas supplied through the RF connection terminal tube flows uniformlythrough the gap between the plasma generation barrier wall and theshowerhead insulating wall.
 31. The apparatus of claim 25, wherein thegas inlet tube is inserted into the opening at the top of the reactorwall with a diameter less than the opening of the reactor wall, and thegas outlet tube is installed in the opening so that the gas supplied tothe reaction space passes through a space between the reactor wall andthe plasma generation barrier wall, and is discharged through a gapbetween the reactor wall and the gas inlet tube.
 32. The apparatus ofclaim 25, wherein the RF connection terminal is connected to theshowerhead assembly through the reactor wall, the plasma generationbarrier wall, and the showerhead insulating wall, and is electricallyinsulated form the reactor wall as well as the plasma generation barrierwall.
 33. The apparatus of claim 11, further comprising a reactor bodyhaving an inert gas inlet port and an inert gas outlet port with on/offvalves and surrounding reactor parts including said substrate carrier.34. The apparatus of claim 33, wherein the RF connection terminal isconnected to the showerhead assembly through the reactor body, thereactor wall, the plasma generation barrier wall, and the showerheadinsulating wall in order to apply an RF power, and is electricallyinsulated from the reactor body, the reactor wall, and the plasmageneration barrier wall.
 35. The apparatus of claim 25, furthercomprising a gas sealer ring covering the substrate carrier andconnecting to the reactor wall in order provide sealing of the innerpart of the reactor.
 36. The apparatus of claim 25, further comprising aheater installed to surround the sidewall of the reactor wall.
 37. Theapparatus of claim 25, further comprising a heater installed underneathof the substrate carrier for heating the substrate.
 38. The apparatus ofclaim 25, wherein the substrate carrier moves up and down so that thesubstrate is loaded into or unloaded from the reaction space.
 39. Amethod of forming a conductive thin film on a substrate, the methodcomprising the steps of: preparing a process gas containing desiredmetallic components; loading a substrate into a reaction space definedin part by a gas injection assembly, and a reactor wall, the gasinjection assembly having a gas injection face and an adjacent sidewall, the gas injection assembly protruding from the reactor wall suchthat a space is formed between the side wall of the gas injectionassembly and the reactor wall; supplying said source gas containingmetallic components to said reaction space through a gas inlet tube;ceasing to supply said source gas and supplying H₂ or H₂ containingpurge gas to said reaction space through said gas inlet tube; generatingplasma to activate said purge gas for a specified period of time whilesaid purge gas is continuously supplied; exhausting gas from thereaction space through the space between the gas injection assembly sidewall and the reactor wall; and purging said reaction space using saidpurge gas; wherein the step of supplying said source gas, the step ofsupplying said purge gas, the step of generating plasma, and the step ofpurging are repeated specified number of times.
 40. The method of claim39, wherein a micro-feeding tube assembly in which a plurality of smalltubes are connected in parallel is installed at the end of said gasinlet tube, and the process gases are supplied through said gas inlettube and then through said micro-feeding tube assembly.
 41. The methodof claim 39, wherein said source gas includes Titanium Tetra-Chloride(TiCl₄).
 42. The method of claim 39, wherein the gas injection assemblycomprises a showerhead assembly.
 43. The method of claim 39, furthercomprising discharging the exhausted gas through a gap between thereactor wall and the gas inlet tube.
 44. The method of claim 39, whereinsaid conductive thin film is titanium nitride (TiN).
 45. The method ofclaim 39, wherein said purge gas includes H₂ and N₂ gases.
 46. Themethod of claim 39, wherein said conductive thin film is titanium metal.